Mr. Han was confident enough to attempt "invoking the gods" because there was one very key item in this study—a jade pendant left by Guan Hengzi.
As for the hidden indication in our book: this jade pendant, in reality, was just an ordinary jade pendant, it wasn't a Magic Treasure, and it wasn't even worth much.
It's just that initially, after Guan Hengzi had deceived Mr. Han, in order to make the "act" seem more convincing, he left this jade pendant with Mr. Han, claiming…"If within ten years you haven't achieved great success, you can use this to settle accounts with me, but if in the future you indeed reach a high position, then this is the token I left with you. When I come to retrieve it, it will be your turn to repay the kindness."